1. Field of the Invention
The present invention concerns acoustics in a wireless device and more particularly, acoustic leak paths in such a device.
2. Description of the Related Art
Almost all mobile communications units include acoustic transducers for broadcasting audio. As is known in the art, such a transducer typically broadcasts audio through a direct port, which leads to the outside of the mobile unit. In addition, for proper operation of the transducer, a back volume is provided in the mobile unit on the other side of the transducer. Normally, a user will hold the mobile unit up against his or her ear, which may provide a seal between the user's head and the mobile unit. In this scenario, the frequency response of the acoustic output for the relevant frequencies is optimal.
There are times, however, when the user may position the mobile unit such that this seal is compromised. For example, the user may move the mobile unit away from his or her head. In this case, there may be a loss in amplitude of the lower end frequencies of the acoustic output, which will lead to an inconsistent acoustic experience for the user. To overcome this issue, many mobile units include leak ports. A leak port is a port that is typically positioned near the direct port of the mobile unit and runs through the mobile unit and exits out the back of the unit. The leak port can help prevent a seal from forming between the user's ear and the mobile unit. Although such a design may result in a less-than-optimal frequency response, as compared to a seal being formed as described above, it does lead to a more consistent acoustic experience for the user if the user re-positions the mobile unit while in use.
Some mobile units may include both low audio and high audio transducers. The low audio transducer is typically used for interconnect calls, while the high audio is generally reserved for dispatch communications. In this type of mobile unit, the low audio transducer must be sealed off from the rest of the mobile unit to prevent audio from the high audio transducer from leaking out of the direct port of the low audio transducer. As such, leak ports are constrained as to where they may be positioned, as they too must be isolated from the high audio transducer. In addition, leak ports typically reduce the aesthetic appearance of the mobile unit, and they make the mobile unit more susceptible to contaminants entering the unit.